1. Field of the Invention
The invention relates to a frictional coupling, especially a synchronization device of a gear mechanism, with at least two coupling bodies which come into contact during engagement of the coupling, wherein one coupling body consists of one ring-shaped base body of metal with, at least, one flat, conical or cylindrical carrier surface to which a frictional layer is attached, and at least one other coupling body of a counter body, preferably also made of metal, which has a counter surface which works together with the frictional layer.
2. The Prior Art
Frictional couplings as well as also synchronization devices of this type are already known in various embodiments from multiple sources. They have the object to create a frictional contact between structural parts rotating a different numbers of revolutions and, in such a way, to make the numbers of revolutions the same. Primarily, those types of frictional couplings are used mainly in motorized vehicles for the synchronization of gear mechanisms to facilitate their shifting and the gear change. Especially, conical frictional systems, prior to being put into operation, in installation and in the new condition of the surfaces brought into frictional contact, exhibit high frictional values during frictional contact which are due to the manufacturing condition of the surfaces of the frictional pairing and make the first shifting of the coupling disadvantageously difficult. If the coupling bodies to come into frictional contact with one another are pressed or hit against one another with a large force during transport prior to installation or during installation itself, there can even be clamping or damage to the edges, by which the first shifting movements can be seriously impaired or even made impossible. These disadvantages are only reduced or eliminated after several shifting procedures of the new coupling or of the new synchronization mechanism as soon as the surfaces of the frictional pairing coming into frictional contact are somewhat smoothened off and have come to fit to one another.
A frictional pairing with a thin, quickly-closing insertion layer on one of frictional bodies is described in DE-OS 2 264 275. This insertion layer, however, in an exothermal reaction is said to form conversion products that act like emery, whereas also binding agents can be used which burn or crack and, in so doing, leave carbon residues behind. In so doing, the counter frictional surface are said to be rapidly freed from all impurities and the desired surface quality quickly achieved. As is, however, mentioned later, the substances formed in the insertion process fall out as a strong expulsion substance, so that this solution is only sensible for use in open systems, for example, in brakes. In closed systems such as lubricated frictional couplings or synchronization devices running in an oil bath, this expulsion substance impurifies the lubricant or the oil and thus acts bothersome and functionally hindering by, for example, penetrating the bearing.
It is thus the object of the invention to further develop the known frictional couplings and synchronization devices with closed systems in such a way that the identified disadvantages of the known embodiments can be avoided through continuous uninhibited function and the operation in the new condition can be facilitated. Especially, the so-called green shiftability of the gear train in synchronization device should be improved.